Oxygenation device

ABSTRACT

This invention relates to apparatus and method for dissolving a gas into a liquid, and particularly relates to apparatus and method for increasing the oxygen content of water by introducing oxygen bubbles into water flowing through a venturi under laminar flow. This invention also relates to maximizing and controlling the laminar flow of water through said venturi so as to maximize mass transfer of oxygen into said water.

FIELD OF THE INVENTION

[0001] This invention relates to apparatus and method for dissolving a gas into a liquid, and particularly relates to apparatus and method for increasing the oxygen content of water by introducing oxygen bubbles into water flowing through a venturi under laminar flow. This invention also relates to maximizing and controlling the laminar flow of water through said venturi so as to maximize mass transfer of oxygen into said water.

BACKGROUND OF THE INVENTION

[0002] There has been great interest expressed in the prior art in introducing oxygen into water as well as controlling the rate of mass transfer of oxygen absorbed by water.

[0003] Such interest has been expressed in a variety of fields including maintaining desired oxygen levels at beaches or in aquaculture such as fish farms or the like. Oxygenation is used throughout the world to improve water quality in aquaculture. Acquaculture generally includes the field of fish farming or the like. Moreover oxygenation systems have been used to improve water quality of stagnant ponds as well as in sanitation systems, wastewater and municipal drinking water.

[0004] There are also those who believe that water having increased levels of dissolved oxygen may be ingested by humans and animals and have beneficial results to the metabolism and general well being of humans and animals. Studies are currently taking place for athletics, asthma, lung disorders and diabetes.

[0005] Accordingly a great number of method and processes have heretofore been used by others.

[0006] For example, U.S. Pat. No. 5,783,118 relates to a process for generating micro-bubbles into a body of liquid and includes immersing a tubular member defining a chamber having closed and open ends in a body of liquid with the closed end facing upwards and the open end downward in the body of liquid; pressurizing the interior of the chamber adjacent its closed end with a gas to maintain a level of liquid within the tubular member at a desired operating level.

[0007] Furthermore U.S. Pat. No. 5,167,878 relates to an aeration device which includes a nozzle, liquid delivery means, and an air delivery means. This can be contrasted with a device shown in U.S. Pat. No. 4,162,970 which relates to an injector for dispersion of a gas into a liquid and comprises a gas inlet, a liquid inlet, and a mixing chamber communicating with said inlets and having an inlet and an outlet, wherein the inlet of the mixing chamber is substantially round in cross section and the outlet is substantially slit-shaped, whereby the kinetic energy of propulsion can be utilized with high efficiency to produce very fine gas bubbles.

[0008] Yet another arrangement is shown in U.S. Pat. No. 4,971,731 which relates to a micro-bubble generator having tubular housing with an inlet end and an outlet end. Located co-axially within the housing is an inner member with an elongated, tapered exterior surface. The porous tubular sleeve is mounted between the housing and the inner member co-axially therewith to define with the cylindrical interior surface of the housing an elongated air chamber of annular cross section. The porous sleeve has a cylindrical inner surface that defines with the exterior surface of the inner member an elongated liquid flow chamber of thin, annular cross section.

[0009] Also U.S. Pat. No. 5,073,309 relates to a device for dispersion of a gaseous phase in liquid phase comprising at least one venturi ejector having a convergent nozzle for admitting a liquid, a neck with means for admitting a gas, a divergent nozzle and an extension of the divergent nozzle with an extension piece of a diameter equal to or larger than the diameter of the end of the divergent nozzle in communication with the end of the divergent nozzle.

[0010] Furthermore U.S. Pat. No. 5,091,118 relates to an apparatus for dissolving gas such as oxygen into a liquid such as water, having a low concentration of gas. The apparatus has an inlet, an outlet and a central region therebetween and as walls defining an interior adapted for dissolving gas in a liquid.

[0011] Yet another U.S. Pat. No. 4,308,138 relates to a device for aerating lakes, the main part of which is an elongate casing having a longitudinal water passage through it. Between the inlet and outlet of this passage there is a frusto-conical segment converging to a restricted outlet opening and a cylindrical barrel segment spaced down stream of, and in axial alignment with, the frusto-conical segment. Surrounding and including the axial space between the frusto-conical and cylindrical segments is a mixing chamber having a pair of air inlet openings to which air hoses are attached.

[0012] U.S. Pat. No. 3,738,620 relates to the size of air bubbles that can be controlled and tiny bubbles can be formed by introducing water and air through a small passage so that the air enters the water through a meniscus rather than directly at a water/air interface where surface tension is much higher.

[0013] Finally U.S. Pat. No. 4,664,600 teaches a method and system for enriching the oxygen content of a body of water having relatively low oxygen content. The method contemplates providing in a pipeline communicating with a body of water, pressurized, flowing aqueous liquid stream that is at a pressure that is greater than ambient and supersaturated with respect to the dissolved oxygen concentration thereof.

[0014] These and other structures and methods taught by the prior art teach relatively complicated structures and methods.

[0015] It is an object of this invention to provide an improved method of increasing the oxygen content of water.

SUMMARY OF THE INVENTION

[0016] It is an object of this invention to provide an improved apparatus for dissolving a gas into a liquid comprising venturi means for receiving a flow of said liquid there through; diffuser means associated with said venturi means for diffusing said gas into said liquid flow; means for controlling said liquid through said venturi means in a laminar zone as said gas is introduced into said liquid.

[0017] It is a further aspect of this invention to provide a method of increasing the oxygen content of water comprising flowing said water through a venturi having an oxygen diffuser associated with said venturi; maintaining laminar flow of said water through said venturi when introducing oxygen through said diffuser into said water.

[0018] It is yet another aspect of this invention to provide a method of increasing and maintaining the mass transfer of oxygen into a body of water comprising providing a passage between said body of water and venturi, said venturi having a throat section; drawing on said body of water for pressurized laminar flow through said venturi; introducing oxygen through a diffuser associated with said throat section of venturi so as to introduce oxygen bubbles into said laminar flow of said water through said venturi; controlling said water and oxygen so as to maximize the laminar flow rate of said water through said venturi.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] A detailed description of the preferred embodiments is provided herein below by way of example only and with reference to the following drawings, in which:

[0020]FIGS. 1a and 1 b are full sided cross-sectional views of the apparatus described herein.

[0021]FIG. 2 in a schematic view of one embodiment of the method described herein.

[0022] In the drawings, preferred embodiments of the invention are illustrated by way of example. It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, and are not intended as a definition of the limits of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023] It is well know that gases are generally soluble in liquids and that the concentration of same depends on the temperature and pressure as well as the composition of the gas and the liquid. The table shown below is an example of the solubility of the major atmospheric gases namely nitrogen, oxygen and argon in milligrams per liter as a function of the pressure and gas composition at 15° C. in fresh water. Pressure Gas Gas solubility (mg/liter) (atm)^(a) Composition Nitrogen Oxygen Argon Carbon Dioxide 1 Air 16.36 10.07 0.62 0.63 1 Pure gas 20.95 48.09 65.94 1969.97 2 Air 33.00 20.32 1.24 1.27 2 Pure gas 42.26 97.01 133.01 3973.72

[0024] One can see from the above that generally speaking the maximum concentration of oxygen than can be dissolved in fresh water at one atmosphere at 15° C. is in the vicinity of 48 mg per liter.

[0025] The apparatus and method to be described herein teaches efficient apparatus and method to increase the concentration of oxygen in water in a continuous process rather than a batch method. Furthermore it should be understood that the apparatus and method to be described herein can be utilized to introduce and maximize a variety of different gases into a variety of different fluids and is not to be limited to introducing oxygen into water.

[0026]FIG. 1 generally illustrates the apparatus 2 which includes the venturi means 4 diffusing means 6 and means for controlling the flow rate of water through the venturi 4 in a manner to be described herein.

[0027] The venturi 4 includes a passage 10, which will communicate with the water and the venturi 4. The venturi 4 is well known to those persons skilled in the art and includes a first converging section 12, a throat section 14 and an exit 16. The venturi 4 generally consists of a short tube with a constricted throatlike passage that increases the velocity and lowers the pressure of a fluid conveyed through it. More specifically the flow rate Q₁ at position 1 is equal to the velocity V₁ and the cross-sectional area of the venturi A₁ at position 1 as illustrated in FIG. 1. Furthermore the flow rate Q₂ at position 2 as shown in FIG. 1 is equal to the velocity of the water V₂ at position 2 times the cross-sectional area A₂ of the throat 14.

[0028] Since the flow rate Q₁ must equal the flow rate Q₂ and the cross-sectional area A₂ is less than the cross-sectional area A₁ the velocity through the throat 14 namely V₂ must be greater than the velocity through the first position V₁.

[0029] It has been found that by maintaining the flow of liquid namely the water through the venturi in the highest possible laminar regime the efficiency of the mass transfer or dissolving of the gas namely oxygen in the water is maximized by maintaining the flow of water at the highest possible laminar regime. If the flow rate of the water through the venturi is increased into the turbulent regime the gas is stilled dissolved in the liquid but such mass transfer is not as efficient as if the flow of the water is maintained in the laminar regime. In other words if the velocity of the water is increased to the point of turbulence the concentration of oxygen dissolved in the water is reduced.

[0030] The introduction of the gas or oxygen is accomplished by utilizing diffuser means, such as a diffuser which comprises of a ring co-axially disposed about the throat 14 as best illustrated in FIG. 1. The diffuser in one embodiment includes holes or orifices having a size of 0.015 inches. Although in other embodiments the holes may have a size of 12 to 16 thousandths of an inch. The size of the holes in the diffuser and throat section of the venturi is selected depending on the amount of oxygen desired to be absorbed into the water. The throat 14 and diffuser 6 is properly sealed therebetween such as welding or the like. Furthermore the throat 14 includes the appropriate holes so that the diffuser 6 can communicate with the interior of the venturi.

[0031] The diffuser and the diffuser may be made from a variety of materials. In one embodiment both the diffuse and venturi are made from stainless steel or the like.

[0032] The water is pumped through the venturi from passage 10 through the constriction 14 past the throat section 14 where oxygen bubbles are introduced into the laminar flow of the water by the diffuser 6.

[0033] As stated above the maximum efficiency of gas transfer occurs at the highest possible laminar flow of the water through the venturi 4. It is believed that the laminar flow of the water of the venturi tends to “smear” or “stretch” the generally circular bubbles into an oval or stretched version of a bubble, which has increased contact with the liquid thereby increasing mass transfer or dissolving of the oxygen into the water. If the flow of water is increased so that it becomes turbulent the bubbles no longer tend to smear or stretch but rather are dispersed and substantially circular, which decreases the area of mass transfer and thereby decreases the concentration of oxygen dissolved in the water.

[0034] As the gas is injected into the venturi stream, the gas stream is thinly stretched along the boundary layer of the venturi wall. This elongation is caused by the high velocity and force of the water namely the kinetic energy of the water at this point. Since the water is in the laminar flow regime, the micro-bubbles of gas are elongated or stretched along the wall of the venturi exposing the maximum amount of surface area possible to the water or liquid. The higher the exposed surface area the more diffusion of the gas into the water. The mass of water smears the elongated or bubble against the boundary layer or wall increasing the surface of the oxygen bubble to the water surface therefore increasing mass transfer.

[0035] It is found in one embodiment that water can be pressurized to 20 psig or greater. The oxygen may be pressurized into the diffuser at a pressure which is the same as the water or slightly greater. In other embodiments the pressure of the water may be increased to 60 to 80 psig.

[0036] Furthermore the size of the holes in the diffuser are sized so as to minimize the size of the bubbles being introduced into the water and in one embodiment comprise of orifices in the diffuser having the size of 0.015 inches.

[0037] The apparatus shown in FIG. 1 includes control means 8 which are utilized to control the flow of water through the venturi in a laminar matter as described above. Such control means 8 can include for example pumping means which are utilized to pressurize the water through the venturi in a controlled manner. The control means 8 may also include rheostats, computer means or the like.

[0038] Furthermore it has been found that the colder and higher the pressure of the water flow the better the mass transfer. However, there are limits to this namely water freezes below 32° F. and accordingly fresh water can not be frozen below 32° F. Furthermore although a higher pressure of water namely higher velocity will increase the stretching of the bubble as well as its mass transfer if the pressure of the water is increased too high the laminar flow becomes unstable and turns into turbulent flow producing many various sizes of bubbles and decreases the mass transfer.

[0039] Accordingly the apparatus described above in the method to increase the oxygen content of water which consists essentially of flowing the water through the venturi 4, having an oxygen diffuser 6 associated with the venturi 4 and maintaining laminar flow of the water through the venturi when introducing oxygen into the diffuser 6.

[0040] By way of example water being introduced into the venturi 4 has an oxygen content of 8-9 mg/, is pumped in at 40-60 psig at a temperature of 4° C. and exits at 48 to 50 mg/l.

[0041] More specifically the method described herein can be used to increase and maintain the mass transfer of oxygen into a body of water, which consists of:

[0042] 1. providing a passage 10 between a body water and a venturi 6 having a throat section 14;

[0043] 2. drawing on the body of water for pressurized laminar flow through the venturi 4;

[0044] 3. introducing oxygen through a diffuser 6 associated with the throat section 14 of the venturi 4 so as to introduce oxygen bubbles into the laminar flow of the water through the venturi 4;

[0045] 4. controlling the water and oxygen so as to maximize the laminar flow of the water.

[0046] Moreover the oxygenated water that exits from the venturi may be collected and bottled for future use. Humans or animals can use this bottled water. Many believe that oxygenated water:

[0047] 1. bolsters the immune system;

[0048] 2. treats infections and diseases;

[0049] 3. aids in vitamin absorption;

[0050] 4. helps the individual or animal feel more energetic;

[0051] 5. better taste.

[0052] Moreover the invention described herein can be used in much larger applications as for example shown schematically in FIG. 2. FIG. 2 illustrates an application in municipal water which is first put though a water softening system 30 which can be equipped with a carbon filtration system. The water and filter system 30 can be first used to soften the water by removing calcium or the like as well as being filtered with undesirable suspended product in the water. The purpose of the water softening and filtration system 30 is utilized to remove calcium, chlorine, and other odorous products that may be in the water.

[0053] Thereafter the water may be introduced into a distillation step 40 where the water is distilled and condensed so as to leave behind salts and minerals. The distilled water may then pass through an ultraviolet filter 50 so as to further ensure the safe drinking of the water in a manner well known to those persons skilled in the art. The water may then be pumped to a cooler so as to cool the water between 32° F. and 40° F. As referred to earlier the colder the water the more oxygen that can be dissolved in the water. Thereafter the water can be introduced to the venturi as described above.

[0054] Moreover the invention described herein may be utilized as follows:

[0055] 1. the oxygenated water can be used in the pharmaceutical area as a medium for growth of aerobic biomass germs, bacteria, viruses, cultures since the water has the metabolism of an organism will be improved and the growth of the organism will be healthier and more rapidly increasing.

[0056] Although the preferred embodiment as well as the operation and use have been specifically described in relation to the drawings, it should be understood that variations in the preferred embodiment could be achieved by a person skilled in the trade without departing from the spirit of the invention as claimed herein 

I claim:
 1. Apparatus for dissolving a gas into a liquid comprising: (a) venturi means for receiving a flow of said liquid there through; (b) diffuser means associated with said venturi means for diffusing said gas into said liquid flow; (c) means for controlling said liquid through said venturi means in a laminar zone as said gas is introduced into said liquid.
 2. Apparatus as claimed in claim 1 wherein said diffuser means comprises a micro-bubble diffuser.
 3. Apparatus as claimed in claim 2 wherein said venturi means includes a throat and said micro-bubble diffuser comprises a ring disposed about said throat of said venturi means.
 4. Apparatus as claimed in claim 3 wherein said micro-bubble diffuser includes gas orifices of 0.015 inches or less.
 5. Apparatus as claimed in claim 4 wherein said venturi means is comprised of stainless steel.
 6. A method of increasing the oxygen content of water comprising: (a) flowing said water through a venturi having an oxygen diffuser associated with said venturi; (b) maintaining laminar flow of said water through said venturi when introducing oxygen through said diffuser into said water.
 7. A method as claimed in claim 6 wherein said flow of said water through said venturi is increased to maximize laminar flow of said water so as to maximize the oxygen content of said oxygenated water.
 8. A method as claimed in claim 7 wherein said water temperature is maintained between 32° F. and 40° F.
 9. A method as claimed in claim 8 wherein said water flowing through said venturi is pressurized at 20 psig or greater.
 10. A method as claimed in claim 9 wherein said oxygen is pressurized to said diffuser at a pressure the same as or greater than said water.
 11. A method as claimed in claim 10 further bottling said oxygenated water.
 12. Water produced from the method of claim 11 having a oxygen content of up to 48 mg of oxygen per liter of water.
 13. A method of increasing and maintaining the mass transfer of oxygen into a body of water comprising: (a) providing a passage between said body of water and venturi, said venturi having a throat section; (b) drawing on said body of water for pressurized laminar flow through said venturi; (c) introducing oxygen through a diffuser associated with said throat section of venturi so as to introduce oxygen bubbles into said laminar flow of said water through said venturi; (d) controlling said water and oxygen so as to maximize the laminar flow rate of said water through said venturi.
 14. A method as claimed in claim 13 wherein said bubbles are stretched when introduced into said laminar flow of said water so as to maximize the mass transfer of said oxygen into said water.
 15. A method as claimed in claim 13 wherein said water is cooled to a temperature between 32° F. and 40° F.
 16. A method as claimed in claim 13 wherein said body of water is first softened and filtered.
 17. A method as claimed in claim 16 wherein said body of water is next distilled.
 18. A method as claimed in claim 17 wherein said distilled body of water is stored and subjected to ultra violet treatment.
 19. A method as claimed in claim 18 wherein said treated body of water is cooled between 32° F. and 40° F. prior to being pumped through said venturi. 